1. Field of the Invention
An embodiment of the present invention relates to a method, medium, and apparatus encoding/decoding audio data, and more particularly, to a method, medium, and apparatus encoding/decoding audio data with extension data that can be used to extend the audio data.
2. Description of the Related Art
When encoding and/or decoding audio data, the audio data can be processed using extension data that provides information for extending the available uses for the audio data. As an example, extension data may include data for extending a channel of audio data, data for extending a bandwidth of audio data, data for generating a code for checking for transmission errors in the received audio data, etc. In addition, extension data may further include metadata of audio data, a fill element of audio data, etc.
FIG. 1A illustrates a conventional syntax for audio data and extension data, and FIG. 1B illustrates a corresponding table of exemplary values of the “extension_type” illustrated in FIG. 1A.
A portion of the syntax identified by reference numeral 100 in FIG. 1A is for the hierarchical decoding of the audio data, and another portion of the syntax identified by reference numeral 110 is for the decoding of the extension data. Referring to reference numeral 110, the recited “extension_type” appears after “zero_code”, which is a code indicating the termination of a payload corresponding to the audio data. This syntax “extension_type” is an identification code indicating the type of extension data and enables a decoding unit to parse the type of the extension data in a payload transmitted from an encoding unit. According to the syntax in FIG. 1A, using extension data, the channel or the bandwidth of audio data can be extended, or the bandwidth of the audio data can be extended and a code for checking for transmission errors in the received extension data, the bandwidth of audio data, can be generated.
However, multi-channel audio coding, which can be a very useful Spectral Band Replication (SBR) tool, cannot be implemented by the conventional syntax of FIG. 1A. In other words, the channel and the bandwidth of audio data cannot be simultaneously extended using the extension data in the syntax of FIG. 1A. For example, in a payload shown in FIG. 1C, for bit sliced arithmetic coding (BSAC), the “BSAC Center” indicated by reference numeral 130 cannot be identified by a decoding unit and cannot appear in an encoding terminal. Therefore, with such conventional encoding and decoding of audio data, there is a limit to the available extending of the extension data of the audio data using various methods.